Nexus.Reader/src/NexusReader.UI.Shared/Components/MarkdownEditor.razor

@using Microsoft.JSInterop
@implements IAsyncDisposable
@inject IJSRuntime JS
@inject HttpClient Http

<div class="markdown-editor-container" style="height: @Height; width: @Width;">
    <div id="@EditorId" class="milkdown-editor-wrapper"></div>
    @if (ShowFetchButton)
    {
        <div class="editor-actions">
            <button type="button" @onclick="FetchContentAsync" class="nexus-btn">
                Fetch Markdown Content
            </button>
        </div>
    }
</div>

@code {
    private readonly string EditorId = $"milkdown-editor-{Guid.NewGuid():N}";
    private readonly CancellationTokenSource _cts = new();
    private IJSObjectReference? _module;
    private DotNetObjectReference<MarkdownEditor>? _dotNetHelper;

    [Parameter]
    public bool ShowFetchButton { get; set; } = true;

    [Parameter]
    public string InitialMarkdown { get; set; } = string.Empty;

    [Parameter]
    public EventCallback<string> OnSave { get; set; }

    [Parameter]
    public string Height { get; set; } = "500px";

    [Parameter]
    public string Width { get; set; } = "100%";

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            _dotNetHelper = DotNetObjectReference.Create(this);
            try
            {
                // Import the isolated JavaScript module
                _module = await JS.InvokeAsync<IJSObjectReference>(
                    "import", 
                    "./_content/NexusReader.UI.Shared/js/milkdownWrapper.js"
                );

                // Call the initialization function in the wrapper
                await _module.InvokeVoidAsync("initEditor", EditorId, _dotNetHelper, InitialMarkdown);
            }
            catch (Exception ex)
            {
                // Log the exception gracefully and do not crash the component
                Console.WriteLine($"[MarkdownEditor] Error initializing Milkdown editor: {ex.Message}");
            }
        }
    }

    public async Task FetchContentAsync()
    {
        if (_module is not null)
        {
            try
            {
                // Retrieve the updated markdown from JS
                var markdown = await _module.InvokeAsync<string>("getMarkdownContent", EditorId);
                
                if (OnSave.HasDelegate)
                {
                    await OnSave.InvokeAsync(markdown);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"[MarkdownEditor] Error fetching markdown content: {ex.Message}");
            }
        }
    }

    [JSInvokable]
    public async Task<string> UploadImageFromJs(string filename, string contentType, byte[] fileBytes)
    {
        try
        {
            using var content = new MultipartFormDataContent();
            var fileContent = new ByteArrayContent(fileBytes);
            fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(contentType);
            content.Add(fileContent, "file", filename);

            var response = await Http.PostAsync("/api/media/upload", content, _cts.Token);
            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadFromJsonAsync<NexusReader.Application.DTOs.Media.UploadResultDto>(
                    NexusReader.Application.Common.AppJsonContext.Default.UploadResultDto, _cts.Token);
                return result?.Url ?? string.Empty;
            }
            else
            {
                var errorMsg = await response.Content.ReadAsStringAsync();
                Console.WriteLine($"[MarkdownEditor] Image upload failed: {response.StatusCode} - {errorMsg}");
                return string.Empty;
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[MarkdownEditor] Exception during image upload: {ex.Message}");
            return string.Empty;
        }
    }

    public async ValueTask DisposeAsync()
    {
        try
        {
            _cts.Cancel();
            _cts.Dispose();
        }
        catch
        {
            // Fail silently if cancellation token disposal fails
        }

        try
        {
            if (_module is not null)
            {
                // Clean up the JS editor instance to prevent memory leaks
                await _module.InvokeVoidAsync("destroyEditor", EditorId);
                await _module.DisposeAsync();
            }
        }
        catch (JSDisconnectedException)
        {
            // Fail silently during circuit disconnection
        }
        catch (ObjectDisposedException)
        {
            // Fail silently if JS runtime/module is already disposed
        }
        catch (Exception ex)
        {
            // Log other unexpected errors
            Console.WriteLine($"[MarkdownEditor] Unexpected error during JS cleanup: {ex.Message}");
        }
        finally
        {
            _dotNetHelper?.Dispose();
        }
    }
}